1. Field of the Invention
The present general inventive concept relates to a paper supplying apparatus for a printing device such as printers or copiers.
2. Description of the Related Art
Generally, conventional printing devices such as printers or copiers include a conventional paper supply apparatus for supplying a sheet of paper stored in a cassette to a printing device by picking up sheets of paper one by one from a stack of papers P. As depicted in FIG. 1, a structure of the conventional paper supply apparatus that is widely used is one in which a knock-up plate 11 of a cassette where papers P are stacked is lifted by a lifter 12 so that a front-end of the uppermost sheet paper P can easily contact with a pick-up roller 13. If the stack height of the papers P is reduced as the papers P are fed into the printing device beyond a predetermined point, a motor 20 rotates the lifter 12 to lift the knock-up plate 11, and as a result, the front-end of the uppermost sheet of paper P is lifted to readily contact with the pick-up roller 13. A feeding roller 14, together with the pick-up roller 13, then pushes the sheet of paper P into the printing device.
However, in the structure of the conventional paper supply apparatus, the motor 20 is exclusively used to lift the knock-up plate 11 and must be installed separately. Therefore, the number of parts is increased, and the conventional paper supply apparatus becomes complicated. Additionally, due to the increase in the number of parts with the conventional paper supply apparatus, power consumption increases. Therefore, there is a need to develop a structure in which the paper P can be smoothly supplied to the printing device without the individual motor 20 that is exclusively used to lift the knock-up plate 11.